This invention relates to novel alkyl- and alkenyl-sulfosuccinate starch half-esters. It also relates to a one-step method for the preparation of the sulfosuccinate half-ester, as well as the novel alkyl- and alkenyl-substituted sulfosuccinate half-esters. It further relates to modified starch derivatives which contain, in addition to the alkyl- or alkenyl-sulfosuccinate substituent groups, other substituent groups on the starch base.
Starch half-esters containing sulfonyl groups have been prepared by treating granular starch in an aqueous alkaline suspension with the cyclic dibasic acid anhydrides of ethylenically unsaturated organic acids (e.g. maleic, citraconic, itaconic, and crotonic acid) and then treating the resulting unsaturated starch half-esters with sodium, potassium, or ammonium bisulfite to form the sulfonyl-containing saturated half-esters by addition across the double bond (see U.S. Pat. No. 2,825,727 issued Mar. 4, 1958 to C. G. Caldwell). The derivatives show controlled water absorption, greater clarity, and greater resistance to gelling, as well as lowered gelatinization temperature. Amphoteric sulfosuccinate half-esters of fluidity starch bases have been used as pigment retention aids, especially in high alum systems (see U.S. Pat. No. 4,029,544 issued June 14, 1977 to W. Jarowenko et al.). They are prepared using the procedure of U.S. Pat. No. 2,825,727. A granular fluidity starch base (4-40 W.F.) containing cationic or cationogenic substituent groups is reacted with maleic anhydride to form the starch succinate half-ester and then with a bisulfite to form the sulfosuccinate half-ester. In addition to the controlled amounts of cationic quaternary ammonium ether groups or cationogenic aminoalkyl ether groups and sulfosuccinate groups, the derivatives may contain other substituent groups.
As used herein, the term "amphoteric" starch derivatives refers to starch derivatives wherein anionic and cationic (or cationogenic) groups are bonded to the same or to different reaction sites on the starch molecular through a zwitterionic substituent group or through separate anionic and cationic (or cationogenic) substituent groups. The term "cationic" groups is hereafter intended to include cationogenic groups which are nonionic substituent groups capable of forming cations (e.g. diethylaminoethyl ether groups).
The present invention provides novel alkyl- and alkenyl-sulfosuccinate starch half-esters which are hydrophobic when long chain alkyl and alkenyl groups are present. It also provides modified alkyl- and alkenyl-sulfosuccinate starch half-esters which contain other substituent groups. It further provides a one-step method for introducing the sulfosuccinate or alkyl- or alkenyl-sulfosuccinate groups into the starch molecule.